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Special Issue "Optical Biosensors"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Biosensors".

Deadline for manuscript submissions: closed (31 October 2007)

Special Issue Editor

Guest Editor
Prof. Dr. Luigi Zeni

Professor of Electronics and Optoelectronics, Second University of Naples, Department of Industrial & Information Engineering, Via Roma 29, 81031 Aversa, Italy
Website | E-Mail
Fax: +39 81 5037042
Interests: integrated optical sensors; optical biosensors; optical fiber sensors; structural health monitoring

Special Issue Information

  • Biosensors based on optical fibers
  • Biosensors based on optical planar waveguides
  • Biosensors based on optical resonant micro-cavities
  • Biosensors based on surface plasmon resonance
  • Fluorescence detection techniques+
  • Refractive index measurement techniques
  • Absorbtion and reflectance spectroscopy
  • Microarrays for multiple analytes screening
  • Optofluidics
  • Flow immunosensors
  • Integrated cell counting devices
  • Electrochemiluminescence and phosphorescence
  • Optical detection of molecules and chemicals
  • Biocompatibility of nano-structured materials

Keywords

  • optical
  • fibers
  • planar
  • waveguides
  • resonant
  • micro-cavities
  • surface plasmon resonance
  • fluorescence detection techniques
  • refractive index measurement techniques
  • absorbtion
  • spectroscopy
  • microarrays
  • screening
  • optofluidics
  • flow immunosensors
  • integrated cell counting devices
  • electrochemiluminescence
  • phosphorescence
  • biocompatibility
  • nano-structured materials

Published Papers (22 papers)

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Research

Jump to: Review

Open AccessArticle Opto-Electric Cellular Biosensor Using Optically Transparent Indium Tin Oxide (ITO) Electrodes
Sensors 2008, 8(5), 3257-3270; doi:10.3390/s8053257
Received: 26 January 2008 / Accepted: 16 May 2008 / Published: 19 May 2008
Cited by 22 | PDF Full-text (3935 KB) | HTML Full-text | XML Full-text
Abstract
Indium tin oxide (ITO) biosensors are used to perform simultaneous optical and electrical measurements in order to examine the dynamic cellular attachment, spreading, and proliferation of endothelial cells (ECs) as well as cytotoxic effects when exposed to cytochalasin D. A detailed description of
[...] Read more.
Indium tin oxide (ITO) biosensors are used to perform simultaneous optical and electrical measurements in order to examine the dynamic cellular attachment, spreading, and proliferation of endothelial cells (ECs) as well as cytotoxic effects when exposed to cytochalasin D. A detailed description of the fabrication of these sensors is provided and their superior optical characteristics are qualitatively shown using four different microscopic images. Differential interference contrast microscopy (DICM) images were acquired simultaneously with micro-impedance measurements as a function of frequency and time. A digital image processing algorithm quantified the cell-covered electrode area as a function of time. In addition, cytotoxicity effects, produced by the toxic agent cytochalasin D, were examined using micro-impedance measurements, confocal microscopy images of stained actin-filaments, and interference reflection contrast microscopy (IRCM) capable of examining the bottom morphology of a cell. The results of this study show (1) the dynamic optical and electrical cellular characteristics using optically thin ITO biosensors; (2) qualitative agreement between cell-covered electrode area and electrical impedance during cellular attachment; (3) in vitro cytotoxicity detection of ECs due to 3 mM cytochalasin D. The present opto-electric biosensor system is unique in that a simultaneous and integrated cellular analysis is possible for a variety of living cells. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle High Sensitive Temperature Sensor Using a Liquid-core Optical Fiber with Small Refractive Index Difference Between Core and Cladding Materials
Sensors 2008, 8(3), 1872-1878; doi:10.3390/s8031872
Received: 29 November 2007 / Accepted: 21 February 2008 / Published: 17 March 2008
Cited by 7 | PDF Full-text (136 KB) | HTML Full-text | XML Full-text
Abstract
An intensive temperature sensor based on a liquid-core optical fiber has been demonstrated for the measuring the temperature of the environment. The core of fiber is filled with a mixture of toluene and chloroform in order to make the refractive index of the
[...] Read more.
An intensive temperature sensor based on a liquid-core optical fiber has been demonstrated for the measuring the temperature of the environment. The core of fiber is filled with a mixture of toluene and chloroform in order to make the refractive index of the liquid-core and the cladding of the fiber close. The experiment shows that a temperature sensitivity of about 5 dB/K and a tunable temperature range (from 20 oC to 60 oC) can be achieved. Based on the dielectric-clad liquid core fiber model, a simulation was carried out and the calculated results were in good accord with the experimental measurement. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Cytotoxicity Investigation on Cultured Human Blood Cells Treated with Single-Wall Carbon Nanotubes
Sensors 2008, 8(1), 488-499; doi:10.3390/s8010488
Received: 29 October 2007 / Accepted: 16 January 2008 / Published: 24 January 2008
Cited by 30 | PDF Full-text (207 KB) | HTML Full-text | XML Full-text
Abstract
The single-wall carbon nanotubes (SWCNTs) are one of the new materials ofemerging technologies. They are becoming increasingly studied for the possibleapplications in electronics, optics and biology. In particular, very promising fields ofapplication are the development of optical biosensors and the intracellular drug delivery.Nevertheless,
[...] Read more.
The single-wall carbon nanotubes (SWCNTs) are one of the new materials ofemerging technologies. They are becoming increasingly studied for the possibleapplications in electronics, optics and biology. In particular, very promising fields ofapplication are the development of optical biosensors and the intracellular drug delivery.Nevertheless, there is a paucity of information on their toxicological properties and onpotential human health risk. In the present study the SWCNTs were investigated for thepossible induction of toxicity in human blood cells. Cell growth, viability, apoptosis andmetabolic activity were evaluated in proliferating human peripheral blood lymphocytes. Inun-stimulated human leukocytes primary DNA damage was also evaluated. SWCNTsconcentrations ranging from 1 to 50 μg/ml were tested, and treatment duration varied from6 to 72 h, in accordance with the biological target investigated. A statistically significantdecrease in cell growth was found in cells treated with the highest concentrations (25 and50 μg/ml). Such decrease was not associated to cell death or apoptosis, but it wasdemonstrated to be related to a decrease in metabolic activity, as assessed by resazurinassay. Moreover, treatments of 6 h with SWCNTs concentrations of 1, 5 and 10 μg/mlfailed to induce primary DNA damage on the entire human leukocytes population. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Recent Advances in High-Birefringence Fiber Loop Mirror Sensors
Sensors 2007, 7(11), 2970-2983; doi:10.3390/s7112970
Received: 21 September 2007 / Accepted: 23 November 2007 / Published: 26 November 2007
Cited by 66 | PDF Full-text (342 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in devices and applications of high-birefringence fiber loopmirror sensors are addressed. In optical sensing, these devices may be used as strain andtemperature sensors, in a separate or in a simultaneous measurement. Other describedapplications include: refractive index measurement, optical filters for interrogate
[...] Read more.
Recent advances in devices and applications of high-birefringence fiber loopmirror sensors are addressed. In optical sensing, these devices may be used as strain andtemperature sensors, in a separate or in a simultaneous measurement. Other describedapplications include: refractive index measurement, optical filters for interrogate gratingsstructures and chemical etching control. The paper analyses and compares different types ofhigh-birefringence fiber loop mirror sensors using conventional and microstructured opticalfibers. Some configurations are presented for simultaneous measurement of physicalparameters when combined with others optical devices, for example with a long periodgrating. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Modelling a Peroxidase-based Optical Biosensor
Sensors 2007, 7(11), 2723-2740; doi:10.3390/s7112723
Received: 8 October 2007 / Accepted: 9 November 2007 / Published: 14 November 2007
Cited by 5 | PDF Full-text (289 KB) | HTML Full-text | XML Full-text
Abstract
The response of a peroxidase-based optical biosensor was modelled digitally.A mathematical model of the optical biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments, an enzyme layerand an outer diffusion layer. The digital simulation was carried
[...] Read more.
The response of a peroxidase-based optical biosensor was modelled digitally.A mathematical model of the optical biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments, an enzyme layerand an outer diffusion layer. The digital simulation was carried out using finite differencetechnique. The influence of the substrate concentration as well as of the thickness of both theenzyme and diffusion layers on the biosensor response was investigated. Calculations showedcomplex kinetics of the biosensor response, especially at low concentrations of the peroxidaseand of the hydrogen peroxide. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Glucose Determination by Means of Steady-state and Time-course UV Fluorescence in Free or Immobilized Glucose Oxidase
Sensors 2007, 7(11), 2612-2625; doi:10.3390/s7112612
Received: 18 October 2007 / Accepted: 3 November 2007 / Published: 5 November 2007
Cited by 12 | PDF Full-text (279 KB) | HTML Full-text | XML Full-text
Abstract
Changes in steady-state UV fluorescence emission from free or immobilizedglucose oxidase have been investigated as a function of glucose concentration.Immobilized GOD has been obtained by entrapment into a gelatine membrane. Changes insteady-state UV fluorescence have been quantitatively characterized by means ofoptokinetic parameters and
[...] Read more.
Changes in steady-state UV fluorescence emission from free or immobilizedglucose oxidase have been investigated as a function of glucose concentration.Immobilized GOD has been obtained by entrapment into a gelatine membrane. Changes insteady-state UV fluorescence have been quantitatively characterized by means ofoptokinetic parameters and their values have been compared with those previouslyobtained for FAD fluorescence in the visible range. The results confirmed that greatercalibration ranges are obtained from UV signals both for free and immobilized GOD inrespect to those obtained under visible fluorescence excitation. An alternative method tothe use UV fluorescence for glucose determination has been investigated by using timecourse measurements for monitoring the differential fluorescence of the redox forms of theFAD in GOD. Also in this case quantitative analysis have been carried out and acomparison with different experimental configurations has been performed. Time coarsemeasurements could be particularly useful for glucose monitoring in complex biologicalfluids in which the intrinsic UV fluorescence of GOD could be not specific by consideringthe presence of numerous proteins. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle D-galactose/D-glucose-binding Protein from Escherichia coli as Probe for a Non-consuming Glucose Implantable Fluorescence Biosensor
Sensors 2007, 7(10), 2484-2491; doi:10.3390/s7102484
Received: 3 October 2007 / Accepted: 21 October 2007 / Published: 24 October 2007
Cited by 5 | PDF Full-text (304 KB) | HTML Full-text | XML Full-text
Abstract
D-Galactose/D-glucose-binding protein from E. coli (GGBP) is a monomer thatbinds glucose with high affinity. The protein structure of GGBP is organized in twoprincipal domains linked by a hinge region that form the sugar-binding site. In this workwe show that the mutant form of
[...] Read more.
D-Galactose/D-glucose-binding protein from E. coli (GGBP) is a monomer thatbinds glucose with high affinity. The protein structure of GGBP is organized in twoprincipal domains linked by a hinge region that form the sugar-binding site. In this workwe show that the mutant form of GGBP at the amino acid position 182 can be utilized as aprobe for the development of a non-consuming analyte fluorescence biosensor to monitorthe glucose level in diabetes health care. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle An Optical Biosensor based on Immobilization of Laccase and MBTH in Stacked Films for the Detection of Catechol.
Sensors 2007, 7(10), 2238-2250; doi:10.3390/s7102238
Received: 14 March 2007 / Accepted: 6 June 2007 / Published: 11 October 2007
Cited by 29 | PDF Full-text (291 KB) | HTML Full-text | XML Full-text
Abstract
The fabrication of an optical biosensor by using stacked films where 3-methyl-2-benzothiazolinone hydrazone (MBTH) was immobilized in a hybrid nafion/sol-gelsilicate film and laccase in a chitosan film for the detection of phenolic compounds wasdescribed. Quinone and/or phenoxy radical product from the enzymatic oxidation
[...] Read more.
The fabrication of an optical biosensor by using stacked films where 3-methyl-2-benzothiazolinone hydrazone (MBTH) was immobilized in a hybrid nafion/sol-gelsilicate film and laccase in a chitosan film for the detection of phenolic compounds wasdescribed. Quinone and/or phenoxy radical product from the enzymatic oxidation ofphenolic compounds was allowed to couple with MBTH to form a colored azo-dye productfor spectrophometric detection. The biosensor demonstrated a linear response to catecholconcentration range of 0.5-8.0 mM with detection limit of 0.33 mM and response time of10 min. The reproducibility of the fabricated biosensor was good with RSD value of 5.3 %(n = 8) and stable for at least 2 months. The use of the hybrid materials of nafion/sol-gelsilicate to immobilize laccase has altered the selectivity of the enzyme to various phenoliccompounds such as catechol, guaicol, o-cresol and m-cresol when compared to the non-immobilized enzyme. When immobilized in this hybrid film, the biosensor response onlyto catechol and not other phenolic compounds investigated. Immobilization in this hybridmaterial has enable the biosensor to be more selective to catechol compared with the non-immobilized enzyme. This shows that by a careful selection of different immobilizationmatrices, the selectivity of an enzyme can be modified to yield a biosensor with goodselectivity towards certain targeted analytes. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle A Urea Biosensor from Stacked Sol-Gel Films with Immobilized Nile Blue Chromoionophore and Urease Enzyme
Sensors 2007, 7(10), 2251-2262; doi:10.3390/s7102251
Received: 3 August 2007 / Accepted: 13 September 2007 / Published: 11 October 2007
Cited by 20 | PDF Full-text (226 KB) | HTML Full-text | XML Full-text
Abstract
An optical urea biosensor was fabricated by stacking several layers of sol-gelfilms. The stacking of the sol-gel films allowed the immobilization of a Nile Bluechromoionophore (ETH 5294) and urease enzyme separately without the need of anychemical attachment procedure. The absorbance response of the
[...] Read more.
An optical urea biosensor was fabricated by stacking several layers of sol-gelfilms. The stacking of the sol-gel films allowed the immobilization of a Nile Bluechromoionophore (ETH 5294) and urease enzyme separately without the need of anychemical attachment procedure. The absorbance response of the biosensor was monitoredat 550 nm, i.e. the deprotonation of the chromoionophore. This multi-layer sol-gel filmformat enabled higher enzyme loading in the biosensor to be achieved. The urea opticalbiosensor constructed from three layers of sol-gel films that contained urease demonstrateda much wider linear response range of up to 100 mM urea when compared with biosensorsthat constructed from 1-2 layers of films. Analysis of urea in urine samples with thisoptical urea biosensor yielded results similar to that determined by a spectrophotometricmethod using the reagent p-dimethylaminobenzaldehyde (R2 = 0.982, n = 6). The averagerecovery of urea from urine samples using this urea biosensor is approximately 103%. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Investigation on Clarified Fruit Juice Composition by Using Visible Light Micro-Raman Spectroscopy
Sensors 2007, 7(10), 2049-2061; doi:10.3390/s7102049
Received: 21 September 2007 / Accepted: 1 October 2007 / Published: 3 October 2007
Cited by 12 | PDF Full-text (267 KB) | HTML Full-text | XML Full-text
Abstract
Liquid samples of clarified apple and apricot juices at different productionstages were investigated using visible light micro-Raman spectroscopy in order to assessits potential in monitoring fruit juice production. As is well-known, pectin plays a strategicrole in the production of clarified juice and the
[...] Read more.
Liquid samples of clarified apple and apricot juices at different productionstages were investigated using visible light micro-Raman spectroscopy in order to assessits potential in monitoring fruit juice production. As is well-known, pectin plays a strategicrole in the production of clarified juice and the possibility of using Raman for its detectionduring production was therefore evaluated. The data analysis has enabled the clearidentification of pectin. In particular, Raman spectra of apple juice samples from washedand crushed fruits revealed a peak at 845 cm-1 (typical of pectin) which disappears in theRaman spectra of depectinised samples. The fructose content was also revealed by thepresence of four peaks at 823 cm-1, 872 cm-1, 918 cm-1 and 975 cm-1. In the case of apricotjuice, several Raman fingerprints of β-carotene at 1008, 1159 and 1520 cm-1 were alsohighlighted. Present results resulted interesting for the exclusive use of optical methods forthe quantitative determination of the above-mentioned substances in place of thebiochemical assays generally used for this purpose, which are time consuming and requiredifferent chemical reagents for each of them. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Development of a Surface Plasmon Resonance n-dodecane Vapor Sensor
Sensors 2007, 7(9), 1954-1961; doi:10.3390/s7091954
Received: 7 June 2007 / Accepted: 17 September 2007 / Published: 21 September 2007
Cited by 4 | PDF Full-text (265 KB) | HTML Full-text | XML Full-text
Abstract
Using a high density polyethylene thin film over gold layer, a Surface PlasmonResonance sensor for detecting n-dodecane vapor is developed. Preliminary results will bepresented, showing that samples in the range of a few hundred ppm(V) of n-dodecanevapor in butane gas can be sensed.
[...] Read more.
Using a high density polyethylene thin film over gold layer, a Surface PlasmonResonance sensor for detecting n-dodecane vapor is developed. Preliminary results will bepresented, showing that samples in the range of a few hundred ppm(V) of n-dodecanevapor in butane gas can be sensed. Also, studying the response as a function of time, it isdemonstrated that the sensing process is quickly reversible. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Hybrid Integrated Silicon Microfluidic Platform for Fluorescence Based Biodetection
Sensors 2007, 7(9), 1901-1915; doi:10.3390/s7091901
Received: 24 August 2007 / Accepted: 10 September 2007 / Published: 11 September 2007
Cited by 11 | PDF Full-text (1040 KB) | HTML Full-text | XML Full-text
Abstract
The desideratum to develop a fully integrated Lab-on-a-chip device capable ofrapid specimen detection for high throughput in-situ biomedical diagnoses and Point-of-Care testing applications has called for the integration of some of the novel technologiessuch as the microfluidics, microphotonics, immunoproteomics and Micro ElectroMechanical Systems
[...] Read more.
The desideratum to develop a fully integrated Lab-on-a-chip device capable ofrapid specimen detection for high throughput in-situ biomedical diagnoses and Point-of-Care testing applications has called for the integration of some of the novel technologiessuch as the microfluidics, microphotonics, immunoproteomics and Micro ElectroMechanical Systems (MEMS). In the present work, a silicon based microfluidic device hasbeen developed for carrying out fluorescence based immunoassay. By hybrid attachment ofthe microfluidic device with a Spectrometer-on-chip, the feasibility of synthesizing anintegrated Lab-on-a-chip type device for fluorescence based biosensing has beendemonstrated. Biodetection using the microfluidic device has been carried out usingantigen sheep IgG and Alexafluor-647 tagged antibody particles and the experimentalresults prove that silicon is a compatible material for the present application given thevarious advantages it offers such as cost-effectiveness, ease of bulk microfabrication,superior surface affinity to biomolecules, ease of disposability of the device etc., and is thussuitable for fabricating Lab-on-a-chip type devices. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Detection of Salmonella by Surface Plasmon Resonance
Sensors 2007, 7(8), 1427-1446; doi:10.3390/s7081427
Received: 26 June 2007 / Accepted: 3 August 2007 / Published: 7 August 2007
Cited by 25 | PDF Full-text (1854 KB) | HTML Full-text | XML Full-text
Abstract
This study explores the possibility of simultaneous and specific detection ofSalmonella serovars by surface plasmon resonance (SPR). The Plasmonic® SPR device wasused to develop this rapid assay. The sandwich immunoassay involves the use of apolyclonal anti-Salmonella antibody to simultaneous capture multiple Salmonella
[...] Read more.
This study explores the possibility of simultaneous and specific detection ofSalmonella serovars by surface plasmon resonance (SPR). The Plasmonic® SPR device wasused to develop this rapid assay. The sandwich immunoassay involves the use of apolyclonal anti-Salmonella antibody to simultaneous capture multiple Salmonella serovarspresent in a sample. This is followed by specific detection of the captured serovars usingO-specific anti-Salmonella antibodies. Milk spiked with Salmonella Typhimurium andSalmonella Enteritidis was used as a model system to establish the assay. The assay wasfurther extended to sequentially differentiate between the two Salmonella serovars on asingle SPR chip in a single channel. The assay was proved to work without any additionaldilution or clean-up steps. The sample volume requirement for the assay is only 10 μL. Thelower limits of detection for Salmonella Typhimurium and Salmonella Enteritidis were2.50×105 cells mL-1 and 2.50×108 cells mL-1, respectively. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessCommunication Surface Plasmon Spectroscopic Detection of Saxitoxin
Sensors 2007, 7(7), 1216-1223; doi:10.3390/s7071216
Received: 18 June 2007 / Accepted: 13 July 2007 / Published: 16 July 2007
Cited by 16 | PDF Full-text (244 KB) | HTML Full-text | XML Full-text
Abstract
For the surface-optoelectronic study of Saxitoxin sensing, we fabricated self-assembled calix[4]arene derivative monolayers as the recognition-functional interfaces ona gold surface. An interaction study between Saxitoxin and calix[4]arene derivativemonolayers were performed using surface plasmon resonance (SPR) spectroscopy. Amongthree calix[4]arene derivatives, calix[4]arene crown ether SAM
[...] Read more.
For the surface-optoelectronic study of Saxitoxin sensing, we fabricated self-assembled calix[4]arene derivative monolayers as the recognition-functional interfaces ona gold surface. An interaction study between Saxitoxin and calix[4]arene derivativemonolayers were performed using surface plasmon resonance (SPR) spectroscopy. Amongthree calix[4]arene derivatives, calix[4]arene crown ether SAM showed the highestsensitivity to Saxitoxin. The detection limit of this system is three orders of magnitudelower than that of the mouse bioassay which is the current benchmark for Saxitoxindetection. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Preparation of Silver Nanoparticle and Its Application to the Determination of ct-DNA
Sensors 2007, 7(5), 708-718; doi:10.3390/s7050708
Received: 16 March 2007 / Accepted: 29 May 2007 / Published: 31 May 2007
Cited by 42 | PDF Full-text (881 KB) | HTML Full-text | XML Full-text
Abstract
A new method to prepare silver nanoparticles was reported in this paper, whichbased on aqueous-gaseous phase reaction of silver nitrate solution and ammonia gas. Theproposed method is effective, rapid, and convenient. Transmission electron microscope(TEM) and X-ray diffraction (XRD) were used to characterize the
[...] Read more.
A new method to prepare silver nanoparticles was reported in this paper, whichbased on aqueous-gaseous phase reaction of silver nitrate solution and ammonia gas. Theproposed method is effective, rapid, and convenient. Transmission electron microscope(TEM) and X-ray diffraction (XRD) were used to characterize the structure of the particles,respectively. It was found that the average diameter of the particles was about 10 nm and theshape was spherical. And the strong fluorescence signal of the silver nanoparticles solutioncan be quenched after the adding of the calf thymus DNA (ct-DNA) solution. Thequenched fluorescence intensity was linear with the concentration of ct-DNA in the range of0.5 to 5.0 × 104 ng mL-1 with a detection limit of 0.3 ng mL-1. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Simulation of Optical Microfiber Loop Resonators for Ambient Refractive Index Sensing
Sensors 2007, 7(5), 689-696; doi:10.3390/s7050689
Received: 4 April 2007 / Accepted: 3 May 2007 / Published: 24 May 2007
Cited by 28 | PDF Full-text (195 KB) | HTML Full-text | XML Full-text
Abstract
Based on theoretical modeling and optimization, we exploit the application ofoptical microfiber loop resonators in ambient refractive index sensing. We set up a reliabletheoretical model and optimize the structural parameters of microfiber loop resonatorsincluding the radius of the microrfiber, the radius of the
[...] Read more.
Based on theoretical modeling and optimization, we exploit the application ofoptical microfiber loop resonators in ambient refractive index sensing. We set up a reliabletheoretical model and optimize the structural parameters of microfiber loop resonatorsincluding the radius of the microrfiber, the radius of the loop and the length of the couplingregion for higher sensitivity, wider dynamic measurement range, and lower detection limit.To show the convincible and realizable sensing ability we perform the simulation ofsensing an extreme small variation of ambient refractive index by employing a set ofexperimental data as the parameters in the expression of intensity transmission coefficient,and the detection limit reaches to a variation of ambient refractive index of 10-5 refractiveindex unit (RIU). This has superiority over the existing evanescent field-basedsubwavelength-diameter optical fiber refractive index sensor. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Guided-Wave Optical Biosensors
Sensors 2007, 7(4), 508-536; doi:10.3390/s7040508
Received: 23 March 2007 / Accepted: 24 April 2007 / Published: 25 April 2007
Cited by 68 | PDF Full-text (579 KB) | HTML Full-text | XML Full-text
Abstract
Guided-wave optical biosensors are reviewed in this paper. Advantages related to optical technologies are presented and integrated architectures are investigated in detail. Main classes of bio receptors and the most attractive optical transduction mechanisms are discussed. The possibility to use Mach-Zehnder and Young
[...] Read more.
Guided-wave optical biosensors are reviewed in this paper. Advantages related to optical technologies are presented and integrated architectures are investigated in detail. Main classes of bio receptors and the most attractive optical transduction mechanisms are discussed. The possibility to use Mach-Zehnder and Young interferometers, microdisk and microring resonators, surface plasmon resonance, hollow and antiresonant waveguides, and Bragg gratings to realize very sensitive and selective, ultra-compact and fast biosensors is discussed. Finally, CMOS-compatible technologies are proved to be the most attractive for fabrication of guided-wave photonic biosensors. Full article
(This article belongs to the Special Issue Optical Biosensors)

Review

Jump to: Research

Open AccessReview Evanescent field Sensors Based on Tantalum Pentoxide Waveguides – A Review
Sensors 2008, 8(2), 711-738; doi:10.3390/s8020711
Received: 5 November 2007 / Accepted: 29 January 2008 / Published: 6 January 2008
Cited by 61 | PDF Full-text (1124 KB) | HTML Full-text | XML Full-text
Abstract
Evanescent field sensors based on waveguide surfaces play an important rolewhere high sensitivity is required. Particularly tantalum pentoxide (Ta2O5) is a suitablematerial for thin-film waveguides due to its high refractive index and low attenuation.Many label-free biosensor systems such as
[...] Read more.
Evanescent field sensors based on waveguide surfaces play an important rolewhere high sensitivity is required. Particularly tantalum pentoxide (Ta2O5) is a suitablematerial for thin-film waveguides due to its high refractive index and low attenuation.Many label-free biosensor systems such as grating couplers and interferometric sensors aswell as fluorescence-based systems benefit from this waveguide material leading toextremely high sensitivity. Some biosensor systems based on Ta2O5 waveguides alreadytook the step into commercialization. This report reviews the various detection systems interms of limit of detection, the applications, and the suitable surface chemistry. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessReview Optical Fiber Sensing Using Quantum Dots
Sensors 2007, 7(12), 3489-3534; doi:10.3390/s7123489
Received: 19 November 2007 / Accepted: 20 December 2007 / Published: 21 December 2007
Cited by 61 | PDF Full-text (1618 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in the application of semiconductor nanocrystals, or quantumdots, as biochemical sensors are reviewed. Quantum dots have unique optical properties thatmake them promising alternatives to traditional dyes in many luminescence basedbioanalytical techniques. An overview of the more relevant progresses in the application
[...] Read more.
Recent advances in the application of semiconductor nanocrystals, or quantumdots, as biochemical sensors are reviewed. Quantum dots have unique optical properties thatmake them promising alternatives to traditional dyes in many luminescence basedbioanalytical techniques. An overview of the more relevant progresses in the application ofquantum dots as biochemical probes is addressed. Special focus will be given toconfigurations where the sensing dots are incorporated in solid membranes and immobilizedin optical fibers or planar waveguide platforms. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessReview Non-invasive Optical Biosensor for Probing Cell Signaling
Sensors 2007, 7(10), 2316-2329; doi:10.3390/s7102316
Received: 24 September 2007 / Accepted: 15 October 2007 / Published: 16 October 2007
Cited by 46 | PDF Full-text (396 KB) | HTML Full-text | XML Full-text
Abstract
Cell signaling mediated through a cellular target is encoded by spatial andtemporal dynamics of downstream signaling networks. The coupling of temporal dynamicswith spatial gradients of signaling activities guides cellular responses upon stimulation.Monitoring the integration of cell signaling in real time, if realized, would
[...] Read more.
Cell signaling mediated through a cellular target is encoded by spatial andtemporal dynamics of downstream signaling networks. The coupling of temporal dynamicswith spatial gradients of signaling activities guides cellular responses upon stimulation.Monitoring the integration of cell signaling in real time, if realized, would provide a newdimension for understanding cell biology and physiology. Optical biosensors includingresonant waveguide grating (RWG) biosensor manifest a physiologically relevant andintegrated cellular response related to dynamic redistribution of cellular matters, thusproviding a non-invasive means for cell signaling study. This paper reviews recentprogresses in biosensor instrumentation, and theoretical considerations and potentialapplications of optical biosensors for whole cell sensing. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessReview Raman Spectroscopy Cell-based Biosensors
Sensors 2007, 7(8), 1343-1358; doi:10.3390/s7081343
Received: 29 June 2007 / Accepted: 25 July 2007 / Published: 26 July 2007
Cited by 125 | PDF Full-text (388 KB) | HTML Full-text | XML Full-text
Abstract
One of the main challenges faced by biodetection systems is the ability to detectand identify a large range of toxins at low concentrations and in short times. Cell-basedbiosensors rely on detecting changes in cell behaviour, metabolism, or induction of celldeath following exposure of
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One of the main challenges faced by biodetection systems is the ability to detectand identify a large range of toxins at low concentrations and in short times. Cell-basedbiosensors rely on detecting changes in cell behaviour, metabolism, or induction of celldeath following exposure of live cells to toxic agents. Raman spectroscopy is a powerfultechnique for studying cellular biochemistry. Different toxic chemicals have differenteffects on living cells and induce different time-dependent biochemical changes related tocell death mechanisms. Cellular changes start with membrane receptor signalling leading tocytoplasmic shrinkage and nuclear fragmentation. The potential advantage of Ramanspectroscopy cell-based systems is that they are not engineered to respond specifically to asingle toxic agent but are free to react to many biologically active compounds. Ramanspectroscopy biosensors can also provide additional information from the time-dependentchanges of cellular biochemistry. Since no cell labelling or staining is required, the specifictime dependent biochemical changes in the living cells can be used for the identificationand quantification of the toxic agents. Thus, detection of biochemical changes of cells byRaman spectroscopy could overcome the limitations of other biosensor techniques, withrespect to detection and discrimination of a large range of toxic agents. Furtherdevelopments of this technique may also include integration of cellular microarrays forhigh throughput in vitro toxicological testing of pharmaceuticals and in situ monitoring ofthe growth of engineered tissues. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessReview Recent Development in Optical Fiber Biosensors
Sensors 2007, 7(6), 797-859; doi:10.3390/s7060797
Received: 21 May 2007 / Accepted: 1 June 2007 / Published: 4 June 2007
Cited by 108 | PDF Full-text (749 KB) | HTML Full-text | XML Full-text
Abstract
Remarkable developments can be seen in the field of optical fibre biosensors in the last decade. More sensors for specific analytes have been reported, novel sensing chemistries or transduction principles have been introduced, and applications in various analytical fields have been realised. This
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Remarkable developments can be seen in the field of optical fibre biosensors in the last decade. More sensors for specific analytes have been reported, novel sensing chemistries or transduction principles have been introduced, and applications in various analytical fields have been realised. This review consists of papers mainly reported in the last decade and presents about applications of optical fiber biosensors. Discussions on the trends in optical fiber biosensor applications in real samples are enumerated. Full article
(This article belongs to the Special Issue Optical Biosensors)

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